<!DOCTYPE html>
<html>
    <head>
        <meta charset="utf-8" />
        <style>
            body{
                display: grid;
                grid-template-rows: 10vh 75vh 10vh;
                grid-template-columns: 300px auto 300px;
                gap:10px;
            }
            header,aside,article,footer {
                background-color: lightgray;
            }
            header,footer {
                grid-column-start: 1;
                grid-column-end: 4;
            }
        </style>
    </head>
    <body>
        <header>header</header>
        <!-- <header>header</header>
        <header>header</header> -->
        <aside>left</aside>
        <article>article</article>
        <aside>right</aside>
        <footer>footer</footer>
        <!-- <footer>footer</footer>
        <footer>footer</footer> -->
    </body>
</html>